Four-joint bionic robotic fish based on Bricard mechanism

Abstract

The invention discloses a four-joint bionic robotic fish based on a Bricard mechanism. The appearance of the four-joint bionic robotic fish is a shark. The novel health care pillow consists of a head part (1), a waist part (2) and a tail part (3). A battery, a circuit board and a pair of pectoral fins are arranged in the head part (1). The waist part (2) is divided into three joints which are respectively driven by an underwater steering engine; and the tail part (3) is based on a triple symmetric Bricard mechanism and consists of a connecting rod I (3-3-1), a connecting rod II (3-3-2), a connecting rod III (3-3-3), a connecting rod IV (3-3-4), a connecting rod V (3-3-5), a cylindrical pin (3-3-6) and a connecting rod VI (3-3-7). The first connecting rod and the sixth connecting rod are fixed to the third waist joint through hinges, and the other connecting rods are connected through hinges pairwise. Each joint of the robotic fish swings according to a preset rule by controlling a single steering engine, the movement speed and direction are changed by controlling the rotating speed and the rotating angle of the motor, and the robotic fish floats or dives by controlling the steering direction, the speed and the rotating angle of the underwater steering engine. The shape and the motion mode of the robotic fish imitate sharks, so that the robotic fish has unique advantages in the fields of biological research, ecological monitoring and the like.

Description

Technical Field

[0001] The present invention relates to a four-joint bionic robotic fish based on a triple-symmetry Bricard mechanism, and more particularly to a bionic tail fin with a single-degree-of-freedom triple-symmetry Bricard closed-chain mechanism as the skeleton. By controlling four waist joint servos and a tail joint servo, the robotic fish can achieve fast underwater maneuverability. The robotic fish has both underwater forward movement and turning capabilities, and can realize functions such as scientific research and education of the robotic fish, underwater environment detection, and obstacle avoidance. Background Art

[0002] As marine resources are increasingly valued by countries, underwater robots have become a research hotspot. As an underwater robot, the bionic robotic fish has characteristics such as low noise and small environmental disturbance. The body / caudal fin propulsion mode (BCF) bionic robotic fish refers to a bionic robotic fish that is propelled by the body / caudal fin propulsion mode. It has advantages such as high speed, high efficiency, and high maneuverability, and is the focus of the research and development of bionic robotic fish in recent years. However, there is still a large gap between the performance of the developed robotic fish prototype and that of natural fish. The Bricard mechanism has few degrees of freedom, high stiffness, flexible and ingenious movement, and requires fewer driving numbers, which is beneficial to the lightweight of the mechanism. Combining the Bricard linkage mechanism with underwater robots will expand the application space of spatial linkage mechanisms and promote the development of underwater robots towards multi-mode and high-efficiency directions. The present invention aims to design a bionic robotic fish based on a triple-symmetry Bricard mechanism to solve the above technical problems. Summary of the Invention

[0003] The technical problems to be solved by the present invention are as follows: There is still a large gap between the performance of the robotic fish prototype and that of fish. Bionic robotic fish often have disadvantages such as large volume, heavy weight, high energy consumption, low comprehensive efficiency, large noise and wake, and poor starting, acceleration, movement flexibility, and concealment performance.

[0004] In view of the defects existing in the prior art, the technical solution adopted by the present invention is: A four-joint bionic robotic fish based on a triple-symmetry Bricard mechanism, in which the tail (3) uses a single-degree-of-freedom Bircard deployable mechanism as the tail fin skeleton (3-3), and the outside is wrapped with a bionic silicone soft material (3-4). The tail fin is driven by an underwater servo (3-2), and the underwater servo is fixed to the waist (3-2) of the fish through a motor bracket (3-1). The tail fin skeleton (3-3) includes link one (3-3-1), link two (3-3-2), link three (3-3-3), link four (3-3-4), link five (3-3-5), cylindrical pin (3-3-6), and link six (3-3-7);

[0005] The described connecting rod one (3-3-1) includes a motor mounting hole (3-3-1-1), a first connecting rod (3-3-1-2), and a bionic silicone soft material mounting hole (3-3-1-3). The first connecting rod (3-3-1-2) adopts a cuboid structure. One end at the top of the connecting rod in the length direction is a boss, with a motor mounting hole (3-3-1-1) in the middle, and a weight-reducing inclined plane at the lower end. On the other side, a mounting notch for the second connecting rod is provided, and a mounting hole for the second connecting rod (3-3-1-3) is machined on the side.

[0006] The described connecting rod two (3-3-2) includes a third connecting rod mounting hole (3-3-2-1), a second connecting rod (3-3-2-2), and a connecting rod one mounting hole (3-3-2-4). The second connecting rod (3-3-2-2) adopts a cuboid structure. One end at the top of the connecting rod in the length direction is a boss, with a motor mounting hole (3-3-2-1) in the middle. A flat position is machined at the end of the other side of the connecting rod, and a connecting rod one mounting hole (3-3-2-4) is machined on the side. A bionic silicone soft material mounting hole (3-3-2-3) is provided in the middle of the connecting rod.

[0007] The described connecting rod three (3-3-3) includes a third connecting rod (3-3-3-1), a connecting rod two mounting hole (3-3-3-2), and a bionic silicone soft material mounting hole (3-3-3-3). The third connecting rod (3-3-3-1) adopts a cuboid structure. A boss is provided above the middle of the connecting rod, and a connecting rod two mounting hole (3-3-3-2) is machined. A notch is cut at one end in the length direction of the connecting rod, and a connecting rod four mounting hole (3-3-3-4) is machined on the side. A bionic silicone soft material mounting hole (3-3-3-3) is provided in the middle of the connecting rod.

[0008] The described connecting rod four (3-3-4) includes a fourth connecting rod (3-3-4-1), a connecting rod five mounting hole (3-3-4-2), and a bionic silicone soft material mounting hole (3-3-4-3). The fourth connecting rod (3-3-4-1) adopts a cuboid structure. A boss is provided above the middle of the connecting rod, and a connecting rod five mounting hole (3-3-4-2) is machined. A flat position is machined at one end in the length direction of the connecting rod, and a connecting rod three mounting hole (3-3-4-4) is machined on the side. A bionic silicone soft material mounting hole (3-3-4-3) is provided in the middle of the connecting rod.

[0009] The described connecting rod five (3-3-5) includes a connecting rod six mounting hole (3-3-5-1), a fifth connecting rod (3-3-5-2), and a bionic silicone soft material mounting hole (3-3-5-3). Among them, the fifth connecting rod (3-3-5-2) adopts a cuboid structure. A boss is provided above one end in the length direction of the connecting rod, and a connecting rod four mounting hole (3-3-5-4) is machined. A notch is machined at the other end in the length direction, and a connecting rod six mounting hole (3-3-5-1) is machined on the side. A bionic silicone soft material mounting hole (3-3-5-3) is provided in the middle of the connecting rod.

[0010] The described cylindrical pin (3-3-6) includes a positioning shoulder (3-3-6-1), a pin shaft (3-3-6-2), and a shaft retaining ring groove (3-3-6-3).

[0011] The described connecting rod six (3-3-7) includes a connecting rod fixing hole (3-3-7-1), a sixth connecting rod (3-3-7-2), and a connecting rod five mounting hole (3-3-7-3). Among them, the sixth connecting rod (3-3-7-2) adopts a cuboid structure. One end in the length direction of the connecting rod is heightened and extended, and a connecting rod five mounting hole (3-3-7-3) is machined at the end of the extended section. A connecting rod fixing hole (3-3-7-1) is machined at the other end in the length direction of the connecting rod.

[0012] The connecting rod one (3-3-1) and the underwater servo (3-2) are connected by a spline pair through the motor mounting hole (3-3-1-1) of the first connecting rod (3-3-1-2). The connecting rod two (3-3-2) is connected to the connecting rod two mounting hole (3-3-1-3) of the connecting rod one (3-3-1) through a revolute pair by the connecting rod one mounting hole (3-3-2-4), and is connected to the connecting rod two mounting hole (3-3-3-2) of the connecting rod three through a revolute pair by the connecting rod three mounting hole (3-3-2-1). The connecting rod three (3-3-3) is connected to the connecting rod three mounting hole (3-3-4-4) of the connecting rod four through a revolute pair by the connecting rod four mounting hole (3-3-3-4). The connecting rod four (3-3-4) is connected to the fifth connecting rod mounting hole (3-3-5-4) of the fifth connecting rod (3-3-5) through a revolute pair by the connecting rod five mounting hole (3-3-4-2). The fifth connecting rod (3-3-5) is connected to the fifth connecting rod mounting hole (3-3-7-3) of the connecting rod six (3-3-7) through a revolute pair by the connecting rod six mounting hole (3-3-5-1). The connecting rod six (3-3-7) is connected to the motor bracket through a bolt pair by the connecting rod fixing hole (3-3-7-1).

[0013] Further defined, the four-joint bionic robotic fish based on the triple-symmetry Bricard mechanism applies a single-degree-of-freedom spatial linkage mechanism to the caudal fin structure of the robotic fish, optimizes its shape according to the biological characteristics of the caudal fin skeleton, and wraps it with a silicone soft material. This not only eliminates the problem of low efficiency of a purely rigid caudal fin but also solves the problem of insufficient rigidity of a purely soft caudal fin. Through the rigid-flexible coupling propulsion method, the robotic fish can obtain excellent movement and turning abilities underwater.

[0014] Further defined, for the four-joint bionic robotic fish based on the triple-symmetry Bricard mechanism, the waist and tail joints of the robotic fish are respectively driven by underwater servomotors. By precisely controlling a single servomotor, each joint can swing according to the set rules. This driving method not only simplifies the control system of the robotic fish but also improves its movement efficiency and response speed.

[0015] Compared with the prior art, the advantages of the present invention are as follows: By controlling a single servomotor, each joint of the robotic fish can swing according to the set rules. By controlling the rotation speed and rotation angle of the underwater servomotor, the movement speed of the robotic fish can be changed, enabling it to move forward quickly and maneuver or turn in the water. By controlling the rotation direction, rotation speed, and rotation angle of the pectoral fin motor, the robotic fish can achieve floating or diving in the water. The shape and swimming mode of the robotic fish both imitate real sharks, giving it unique advantages in the fields of biological research, ecological monitoring, etc. Brief Description of the Drawings

[0016] Figure 1 Four-joint Bionic Robotic Fish Based on Triple-Symmetry Bricard Mechanism

[0017] Figure 2 Structural Diagram of the Tail of the Robotic Fish

[0018] Figure 3 Structural Diagram of the Bionic Skeleton of the Tail Bricard Mechanism

[0019] Figure 4 Structural Diagram of Link 1

[0020] Figure 5 Structural Diagram of Link 2

[0021] Figure 6 Structural Diagram of Link 3

[0022] Figure 7 Structural Diagram of Link 4

[0023] Figure 8 Structural Diagram of Link 5

[0024] Figure 9 Structural Diagram of the Cylindrical Pin

[0025] Figure 10Structural Diagram of Link Six

[0026] Figure 11 Oscillatory Motion Mode

[0027] Figure 12 Structural Diagram of Pectoral Fin Motor Specific Embodiment

[0028] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0029] As Figure 1 shown, a four-joint bionic robotic fish based on a triple-symmetric Bricard mechanism, characterized in that: the overall shape of the bionic shark is streamlined, divided into a head (1), a waist (2) and a tail (3). Among them, the head (1) and the waist joint (2) are both 3D-printed plastic shells, and the tail (3) uses a single-degree-of-freedom Bircard deployable and foldable mechanism as the tail fin skeleton (3-3), and the outside is wrapped with bionic silicone soft material (3-4).

[0030] As Figure 2 shown, the tail fin is driven by an underwater servo (3-2), and the underwater servo is fixed to the waist of the fish (3-2) through a motor bracket (3-1). Its shape conforms to the biological characteristics of the shark's tail and can achieve the kinematic characteristics of reciprocating swing.

[0031] As Figure 3 shown, the tail fin skeleton (3-3) is based on a triple-plane symmetric Bricard mechanism and is a variant design according to the shark tail fin fish bone characteristics and installation conditions, including link one (3-3-1), link two (3-3-2), link three (3-3-3), link four (3-3-4), link five (3-3-5), cylindrical pin (3-3-6), link six (3-3-7). Among them, link three and link four are lengthened to support the bionic silicone soft material and improve the strength of the tail.

[0032] As Figure 4 shown, the link one (3-3-1) includes a motor mounting hole (3-3-1-1), a first link (3-3-1-2) and a bionic silicone soft material mounting hole (3-3-1-3). Link one is installed on the output rotating shaft of the underwater servo and rotates reciprocally through motor control, serving as the power input of the skeleton.

[0033] As Figure 5 shown, the link two (3-3-2) includes a third link mounting hole (3-3-2-1), a second link (3-3-2-2) and a link one mounting hole (3-3-2-4). Link two rotates reciprocally with link one under the drive of link one, and has the same swing angle as link one.

[0034] AsFigure 6 As shown, the third link (3-3-3) includes a third link (3-3-3-1), a second link mounting hole (3-3-3-2), and a bionic silicone soft material mounting hole (3-3-3-3). The third link and the second link are connected by a revolute pair and reciprocally swing around the articulation point of the third link and the fourth link under the drive of the second link;

[0035] As Figure 7 shown, the fourth link (3-3-4) includes a fourth link (3-3-4-1), a fifth link mounting hole (3-3-4-2), and a bionic silicone soft material mounting hole (3-3-4-3). The fourth link is parallel to the third link and reciprocally swings around the articulation point of the third link and the fourth link under the drive of the third link;

[0036] As Figure 8 shown, the fifth link (3-3-5) includes a sixth link mounting hole (3-3-5-1), a fifth link (3-3-5-2), and a bionic silicone soft material mounting hole (3-3-5-3). Since the fifth link is connected to the fixed link, the sixth link, it does not participate in the swinging motion.

[0037] As Figure 9 shown, the cylindrical pin is the connecting and fixing part of all revolute pairs and provides auxiliary support for the links.

[0038] As Figure 10 shown, the sixth link (3-3-7) includes a link fixing hole (3-3-7-1), a sixth link (3-3-7-2), and a fifth link mounting hole (3-3-7-3). The sixth link is fixed to the motor bracket by a bolt pair, providing fixed support and degree-of-freedom limitation for the entire skeleton.

[0039] As Figure 11 shown, the Bricard mechanism bionics the fish tail bone. Its first link reciprocally rotates around the axis of the first link's length. The second link follows the first link. The third link and the fourth link reciprocally swing around the articulation point of the third link and the fourth link under the drive of the second link. The accompanying drawings show the left-turn swinging mode (a) and the right-turn swinging mode (b). By repeatedly executing mode (a) and mode (b), the robotic fish can obtain thrust underwater. Specific usage method:

[0040] By the first link of the bionic fish tail bone reciprocally rotating around the axis of the first link's length, the second link follows the first link, and the third link and the fourth link reciprocally swing around the articulation point of the third link and the fourth link under the drive of the second link. The robotic fish can obtain thrust underwater, thereby realizing forward maneuverability.

[0041] By the waist joint motor deflecting and swinging on a single side in the width direction of the fish body, with the tail fin swinging pattern unchanged, the robotic fish can achieve the movement mode of turning towards the side where the body bends.

[0042] Further defined, the four-joint bionic robotic fish based on the triple-symmetry Bricard mechanism can obtain excellent moving and steering motion capabilities by controlling the single-driven Bricard bionic tail fin and the waist joint.

[0043] Further defined, the four-joint bionic robotic fish based on the triple-symmetry Bricard mechanism can adjust the motion of the robotic fish by controlling the rotation speed and rotation angle of the underwater servo motor, so that the robotic fish has a fast maneuvering mode. By controlling the rotation direction of the underwater servo motor, the waist and the tail can cooperate, so that the robotic fish can turn or avoid obstacles according to the planned path underwater.

[0044] It should be noted that in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0045] The above are only specific embodiments of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A four-joint bionic robotic fish based on the Bricard mechanism, characterized by: The tail (3) uses a single-degree-of-freedom Bircard deployable mechanism as a tail fin skeleton (3-3), and is wrapped with a bionic silicone soft material (3-4) on the outside. The tail fin is driven by an underwater servo (3-2), and the underwater servo is fixed to the waist (3-2) of the fish through a motor bracket (3-1), wherein the tail fin skeleton (3-3) includes a connecting rod 1 (3-3-1), a connecting rod 2 (3-3-2), a connecting rod 3 (3-3-3), a connecting rod 4 (3-3-4), a connecting rod 5 (3-3-5), a cylindrical pin (3-3-6), and a connecting rod 6 (3-3-7); The connecting rod 1 (3-3-1) comprises a motor mounting hole (3-3-1-1), a first connecting rod (3-3-1-2) and a bionic silicone soft material mounting hole (3-3-1-3), wherein the first connecting rod (3-3-1-2) adopts a rectangular parallelepiped structure, a boss is provided at the top of one side in the length direction of the connecting rod, a motor mounting hole (3-3-1-1) is provided in the middle, a weight-reducing inclined surface is provided at the lower end, a connecting rod 2 mounting notch is provided on the other side, and a connecting rod 2 mounting hole (3-3-1-3) is processed on the side; The connecting rod 2 (3-3-2) comprises a third connecting rod mounting hole (3-3-2-1), a second connecting rod (3-3-2-2) and a connecting rod first mounting hole (3-3-2-4), wherein the second connecting rod (3-3-2-2) adopts a rectangular parallelepiped structure, the top end of one side of the connecting rod in the length direction is a boss, a motor mounting hole (3-3-2-1) is arranged in the middle, a flat position is processed at the end of the other side of the connecting rod, and a connecting rod first mounting hole (3-3-2-4) is processed on the side, and a bionic silicone soft material mounting hole (3-3-2-3) is arranged in the middle of the connecting rod; The connecting rod three (3-3-3) comprises a third connecting rod (3-3-3-1), a connecting rod two mounting hole (3-3-3-2) and a bionic silicone soft material mounting hole (3-3-3-3), wherein the third connecting rod (3-3-3-1) adopts a rectangular parallelepiped structure, a boss is arranged above the middle of the connecting rod, and the connecting rod two mounting hole (3-3-3-2) is processed, a notch is opened at one end in the length direction of the connecting rod, and a connecting rod four mounting hole (3-3-3-4) is processed on the side, and a bionic silicone soft material mounting hole (3-3-3-3) is arranged in the middle of the connecting rod; The connecting rod four (3-3-4) comprises a fourth connecting rod (3-3-4-1), a connecting rod five mounting hole (3-3-4-2) and a bionic silicone soft material mounting hole (3-3-4-3), wherein the fourth connecting rod (3-3-4-1) adopts a rectangular parallelepiped structure, a boss is arranged above the middle of the connecting rod, and the connecting rod five mounting hole (3-3-4-2) is processed, a flat position is processed at one end in the length direction of the connecting rod, and a connecting rod three mounting hole (3-3-4-4) is processed on the side, and a bionic silicone soft material mounting hole (3-3-4-3) is arranged in the middle of the connecting rod; The connecting rod five (3-3-5) comprises a connecting rod six mounting hole (3-3-5-1), a fifth connecting rod (3-3-5-2) and a bionic silicone soft material mounting hole (3-3-5-3), wherein the fifth connecting rod (3-3-5-2) adopts a rectangular parallelepiped structure, a boss is arranged above one end of the connecting rod in the length direction, and a connecting rod four mounting hole (3-3-5-4) is processed, a notch is processed at the other end in the length direction, and a connecting rod six mounting hole (3-3-5-1) is processed on the side, and a bionic silicone soft material mounting hole (3-3-5-3) is arranged in the middle of the connecting rod; The cylindrical pin (3-3-6) comprises a positioning shaft shoulder (3-3-6-1), a pin shaft (3-3-6-2) and a shaft retaining ring groove (3-3-6-3); The connecting rod six (3-3-7) comprises a connecting rod fixing hole (3-3-7-1), a sixth connecting rod (3-3-7-2) and a connecting rod five mounting hole (3-3-7-3), wherein the sixth connecting rod (3-3-7-2) adopts a rectangular parallelepiped structure, one end of the connecting rod length direction is heightened and extended, and the connecting rod five mounting hole (3-3-7-3) is processed at the end of the extended section, and the connecting rod fixing hole (3-3-7-1) is processed at the other end of the connecting rod length direction; The connecting rod 1 (3-3-1) is connected to the underwater steering gear (3-2) through a spline pair via the motor mounting hole (3-3-1-1) of the first connecting rod (3-3-1-2); the connecting rod 2 (3-3-2) is connected to the connecting rod 2 mounting hole (3-3-1-3) of the connecting rod 1 (3-3-1) through a revolute pair via the connecting rod 1 mounting hole (3-3-2-4); and is connected to the connecting rod 2 mounting hole (3-3-3-2) of the connecting rod 3 through a revolute pair via the connecting rod 3 mounting hole (3-3-2-1); the connecting rod 3 (3-3-3) is connected to the connecting rod 4 mounting hole (3-3-3-4). The connecting rod four is connected to the connecting rod three mounting hole (3-3-4-4) through a rotating pair, the connecting rod four (3-3-4) is connected to the fifth connecting rod mounting hole (3-3-5-4) of the fifth connecting rod (3-3-5) through the connecting rod five mounting hole (3-3-4-2) through a rotating pair, the connecting rod five (3-3-5) is connected to the fifth connecting rod mounting hole (3-3-7-3) of the connecting rod six (3-3-7) through the connecting rod six mounting hole (3-3-5-1) through a rotating pair, and the connecting rod six (3-3-7) is connected to the motor bracket through the connecting rod fixing hole (3-3-7-1) through a bolt pair.

2. A four-joint bionic robotic fish based on the Bricard mechanism as claimed in claim 1, characterized in that: The waist and tail propulsion of the robot fish adopts a rigid-flexible coupling bionic structure. The single-joint tail uses the Bricard bionic tail fin, in which the triple-sided symmetrical Bricard is used as the skeleton of the tail fin, and the external installation is a silicone soft material. The waist joint is divided into three joints, each of which is driven by an underwater servo. By controlling the waist and tail joints, the robot fish can obtain excellent movement and turning capabilities underwater.

3. A four-joint bionic robotic fish based on the Bricard mechanism as claimed in claim 1, characterized in that The waist and tail joints of the robot fish are driven by underwater servos respectively. Through precise control of a single servo, each joint can swing according to the set rules. This driving method not only simplifies the control system of the robot fish, but also improves its movement efficiency and response speed.

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